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                玩游戏2                </h1>
                <p>时间限制：10s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：128MB</p>			</div>
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                                <h3>题目描述</h3><p><div style="margin: 0cm 0cm 0pt 21pt; text-indent: 21pt"><span style="font-size: medium">游戏是在一个无环的无向图中进行的，每个点上面有一些金币,每次小K可以对一个金币&gt;=2的点，拿走一个金币，并将另一个金币放到它相邻的点上，而游戏中有一个点叫做Target Point,如果在游戏的过程中Target Point上有金币的话，小K就赢了。</span></div>
<div style="margin: 0cm 0cm 0pt 21pt; text-indent: 21pt"><span style="font-size: medium">巧合的是这个游戏是小Z开发的，在得知小K在玩这个游戏之后，为了报上次的一箭之仇，他决定设计金币的分布让小K必败。</span></div>
<div style="margin: 0cm 0cm 0pt 21pt; text-indent: 21pt"><span style="font-size: medium">而小Z深知小K的光环的威力，如果放置的金币太少,小K会马上发现这个游戏是不可能赢的。于是他求助于你，他最多能放多少个金币呢？？</span></div>
<div><span style="font-size: medium">&nbsp;</span></div></p><hr/><h3>输入格式</h3><p><div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 本题有多组数据。</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 第一行，两个整数N,M( 1&lt;=M&lt;=N&lt;=60 ),表示共有N个节点，而M为Targer Point</span></div>
<div><span style="font-size: medium">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 下面有N行,每行为一个长度为N的字符串，如果第i个字符串的第j个字符是'Y',则代表i与j之间有边。</span></div>
<div><span style="font-size: medium">&nbsp;</span></div>
<div><span style="font-size: medium">&nbsp;</span></div></p><hr/><h3>输出格式</h3><p><p><font size="4">最多能放多少个金币,如果答案超过了2*10^9则输出-1</font></p>
<div><span style="font-size: medium">&nbsp;</span></div>
<div><span style="font-size: medium">&nbsp;</span></div></p><hr/><h3>样例输入</h3><pre>3 2
NYN
YNY
NYN
1 1
N
 
 </pre><hr/><h3>样例输出</h3><pre>2
0
</pre><hr/><h3>提示</h3><p>没有写明提示</p><hr/><h3>题目来源</h3><p>没有写明来源</p>
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